The Electric CB750 Project

[JPanichella]

It's been a real long time since I've been here (the color scheme used to be black, right?) but now I'm back with a project to talk about. Last time I posted here was well over a year ago, and I was happily wrenching on my 1978 CB750 every night after work. I received word that my dad was diagnosed with pancreatic cancer, so I immediately left for my hometown to spend time with him in his final months. Coming back to school meant a lot of time catching up on work, not a lot of wrenching time. But now that the sun is out a bit longer and it's not quite so cold outside, things are going back to normal.


Except I'm converting it to electric.


Now I know that people will either receive this warmly or promptly call me an idiot, but I am passionate about this project, about the technology, and about doing something completely unique. I've already got my motor which peaks at 31HP, my motor controller which peaks at 400 amps.


I am designing this thing to be a light weight, short distance ride back and forth to class. I will be using small, light, low capacity lead acid batteries that are easy to charge and cheap to replace. Battery technology makes leaps every day, and if you want bleeding edge technology you certainly pay for it. I'm going to revel in my cheap little lead acid batts until expensive lithium technologies are more attainable.



Here's my motor. It's a D&D Separately Excited Motor. Meaning I get smooth regenerative breaking and very high efficiency. It weighs 62 pounds and measures 6.5" in diameter by about 12 inches long.

My controller is a unit by PG Drives called Sigmadrive. It basically translates the input from my throttle and delivers power from the battery to the motor accordingly. They also control regenerative braking.

This is a contactor, which is like a big safety switch in case things go horribly wrong.

Two Magura twist grip throttles. One to control acceleration and one to control regenerative motor braking.

Sure Power DC/DC Converter. It basically takes my battery pack voltage (72V) and drops it down to a safe voltage for my headlights/signals/12v stuff to run on.


I also have a charger handy. I'm pretty much set aside from batteries, wire, some random switches and doodads. But those are the big components.




And here is the frame it's all getting attached to.

And here is the proposed layout of all the components.

The cylindrical bit is the electric motor, which attaches where the existing motor mounts are. The diagonal portion is the battery pack, six 12V batteries in a line, for a total of 72V. Electric motors have a flat torque curve and require no transmission. The gear ratio will be 5 to 1.


I look forward to the next few weeks of working on this guy. Right now I'm in the process of grinding all the unnecessary bits off the frame and getting the battery box and motor mounted. I'll hopefully have more pictures by the weekend. If you guys have any questions about the technology and all that I'll be glad to answer.

 

[Sonreir]

Nice. I'll be interested to see how this one goes. I was thinking about picking up an electric bike. They sell them at Best Buy for about 8 grand and run from 72V just like yours.

 

[Sonreir]

Also... you gonna rename your bike to CE400?

 

[PHeller]

31hp is a bit down on the power from the 750 engine, and I'd imagine with batteries you'll be fairly close to the same weight.


What should be interesting is the immediate torque.


I'd like to know your budget for the build as well.

 

[JPanichella]

Nice. I'll be interested to see how this one goes. I was thinking about picking up an electric bike. They sell them at Best Buy for about 8 grand and run from 72V just like yours.

That'd be the Brammo Enertia, right?

Those are great little bikes. The new models get 80 miles to a charge (which may not sound like much, but are a big accomplishment in the realm of electric motorcycles). The company that developed them also developed the Ariel Atom!

Here's the batteries I'm going to be using.

 

[JPanichella]

31hp is a bit down on the power from the 750 engine, and I'd imagine with batteries you'll be fairly close to the same weight.


What should be interesting is the immediate torque.


I'd like to know your budget for the build as well.

That 31 HP is peak and from a 500amp controller. Unfortunately, my controller is rated for 100 amps less, so I don't expect to get the full potential of this motor without some upgrades and tweaking.

So far, I have a little under a grand sunk into the electric drivetrain. With batteries it's going to be about 1300. I took my time and got some good deals from companies that were liquidating old stock, and people who were selling off parts from projects that never came to fruition. If you want serious performance the projects can easily climb to several thousand dollars.

 

[lockard666]

cool stuff... i sold a good, running '85 ninja 900 to a guy... he told me that he was going to gut it & make it electric... he specifically wanted a mid 80's kawi 900... something about the frame rails being wider & having more room for batteries... i think the motor was getting mounted to the top of the swingarm... i wish i would have got his contact info so he could send me pics but i never did.... anyway, you got my attention.

 

[pablohoney]

Very cool dude, looking forward to seeing it.

 

[JPanichella]

cool stuff... i sold a good, running '85 ninja 900 to a guy... he told me that he was going to gut it & make it electric... he specifically wanted a mid 80's kawi 900... something about the frame rails being wider & having more room for batteries... i think the motor was getting mounted to the top of the swingarm... i wish i would have got his contact info so he could send me pics but i never did.... anyway, you got my attention.

Kawi and gixxers are commonly used for electric conversions for that reason. He's probably going to cram a bunch of heavy batteries in there and turn it into a bit of a pig (unless he's going lithium). Seems a shame that he's gutting a running bike. Luckily, I can claim that mine never ran. Sold my motor to a buddy who has the same bike for parts.

Electric bikes are interesting because the technology is still in it's infancy, so the trade-offs people make are interesting. I decided to opt for light weight, speed, and short distance. But if I wanted 10 miles more, my bike would weigh over 100 pounds more (with lead acid). Can't wait to see what batteries are like 5 years from now, though.

I spec-ed out a pack of lithium polymer batteries that could get me 40 miles to a charge and only weigh around 50 pounds. But they cost near 1400 bucks...

 

[Big R]

First off, sorry to hear about your Dad. I know no words seem to help, but you have my condolences.

Second, I know nothing about electric motorcycles. But they do intrigue me......

 

[Juggernaut]

This looks to be one interesting project. I have yet to see something battery powered on the roads. Being nearly silent would be cool and very strange at the same time. I can't wait to see what the end result is going to look like.

 

[JPanichella]

This looks to be one interesting project. I have yet to see something battery powered on the roads. Being nearly silent would be cool and very strange at the same time. I can't wait to see what the end result is going to look like.

Here's a pretty cool video of an electric ride. I haven't had a chance to ride one either, so I'm basing everything I know about it off videos like this.

Electric Chopper Test Drive

 

[JPanichella]

First off, sorry to hear about your Dad. I know no words seem to help, but you have my condolences.

Second, I know nothing about electric motorcycles. But they do intrigue me......

Thanks for your kind words. My dad never rode or anything, but he had a chance to see the bike before it was completely torn down to the frame. I plan on building this bike in his honor.

 

[beard]

Thanks for your kind words. My dad never rode or anything, but he had a chance to see the bike before it was completely torn down to the frame. I plan on building this bike in his honor.

ill keep my political and other opinions to myself.
i totally respect the above, after losing my dad at the age of becoming a man.. 17.. i know all of all the stuff that you miss.. and how he still and willl drive you.


as roland deschain ( the gun slinger) from the dark tower series would say:

I do not aim with my hand;
He who aims with his hand has forgotten the face of his father.
I aim with my eye.
I do not shoot with my hand;
He who shoots with his hand has forgotten the face of his father.
I shoot with my mind.

I do not kill with my gun;
He who kills with his gun has forgotten the face of his father.
I kill with my heart.

god speed my friend.. if you ever need any help without question i am here.

 

[Juggernaut]

The gunslinger series was the most amazing story I've ever read. Thanks for the vid. I can't wait to get off work and give it a listen.

 

[JPanichella]

Got some good work done today. Chopped off all the bits and tabs on my frame that I no longer need, and ground them smooth, including the passenger pegs.

 

[liam]

really keen on watching this one develop. make sure to link details and suppliers if you could, there's a lot of thrashed out bikes around that look to me to be begging for a electric heart.

 

[chrisf]

this is going to be fun

 

[rockcitycafe]

very cool, what's the discharge rate on the batteries? I'd be wondering if that will be enough to handle the load of the motor without seeing a big voltage drop at the terminals... C rate I believe it's called? very cool though, I'm sure once you get it working, you can save your pennies and build a NiMH battery for it, should give you much longer rides

 

[JPanichella]

very cool, what's the discharge rate on the batteries? I'd be wondering if that will be enough to handle the load of the motor without seeing a big voltage drop at the terminals... C rate I believe it's called? very cool though, I'm sure once you get it working, you can save your pennies and build a NiMH battery for it, should give you much longer rides

That's the plan. These little lead acid batteries are actually meant for scooters, so they have an acceptable C rate, but they're nothing like the high discharge lithium polymer batteries people are putting in bikes nowadays. I'm going to refer to this pack as my "debug pack". Meaning it'll get me up and running, help me sort out all the electrical gremlins, and if I accidentally blow up a battery I won't cry as hard. My ride to school is less than a few miles, so my goal for now is to just make a bike to ride to school/grocery getter.

The newest, coolest battery tech is LiPo, used in RC cars and planes. They're super light, incredibly high discharge rates, and relatively affordable. The problem right now is that nobody has developed an easy way to charge and balance all of these individual cells, and they can catch fire if not properly charged.

I'm glad to see the amount of interest this project is getting!